Dispensing Nozzle Design and Dispensing Method Thereof

ABSTRACT

A lithography apparatus includes a wafer chuck configured to hold a wafer, a fluid source configured to contain a fluid to be applied towards the wafer during a lithography process, a dispensing nozzle positioned above the wafer chuck and in fluid communication with the fluid source, the dispensing nozzle having an adjustable cross-section, and a mechanical mechanism operable to apply a force towards an outer surface of the dispensing nozzle to change the adjustable cross-section.

PRIORITY

This is a continuation of U.S. patent application Ser. No. 17/203,081,filed on Mar. 16, 2021, which is a division of U.S. patent applicationSer. No. 16/124,579, filed on Sep. 7, 2018, now U.S. Pat. No.10,948,824, which claims priority to U.S. Provisional Patent ApplicationSer. No. 62/691,113, filed on Jun. 28, 2018, the entire disclosure ofwhich is hereby incorporated herein by reference.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experiencedexponential growth. Technological advances in IC materials and designhave produced generations of ICs where each generation has smaller andmore complex circuits than the previous generation. In the course of ICevolution, functional density (i.e., the number of interconnecteddevices per chip area) has generally increased while geometry size(i.e., the smallest component (or line) that can be created using afabrication process) has decreased. This scaling down process generallyprovides benefits by increasing production efficiency and loweringassociated costs. Such scaling down has also increased the complexity ofprocessing and manufacturing ICs.

As the technology of semiconductor fabrication progresses, the formationof precise photolithographic patterns more relies upon the applicationof uniform coating of photoresist materials. A uniform coating ofphotoresist materials is important because thickness variations mayimpact subsequent processing steps. The photoresist material is a liquidthat is coated to form a thin layer on top of a substrate surface, suchas on a semiconductor wafer. Several dispensing methods have beenemployed to apply liquid coating materials onto wafer substrates. Insome applications, spinning wafers are flooded with liquid coatingmaterials dispensed from nozzles. The dispensing nozzles often haveorifices with circular cross-sections. As presently practiced, however,the fluid flow onto the substrate may not be smooth; the uniformity ofthe fluid spread during dispense may be poor; and relatively largeexcess volumes of fluid may be required to achieve acceptable filmthickness uniformities, which can also be time consuming. Therefore, aneed exists for a nozzle and a method for dispensing liquid coatingmaterials that delivers a uniform coating layer while reducing waste andincreasing efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a schematic view of a liquid dispensing apparatus, inaccordance with various embodiments of the present disclosure.

FIG. 2 illustrates a cross-sectional view of a dispensing nozzle that isoperable to vary its cross-sections according to aspects of the presentdisclosure in one or more embodiments.

FIGS. 3A, 3B, 3C, and 3D illustrate a top view of a dispensing nozzlethat is operable to vary its cross-sections according to aspects of thepresent disclosure in one or more embodiments.

FIGS. 4A and 4B illustrate a cross-sectional view of a dispensing nozzlethat is operable to form tapered sidewalls according to aspects of thepresent disclosure in one or more embodiments.

FIG. 5 shows a flow chart of a liquid dispensing method according tovarious aspects of the present disclosure.

FIG. 6 shows a flow chart of steps in an operation of the method of FIG.5 according to various aspects of the present disclosure.

FIGS. 7A, 7B, and 7C shows schematic views of liquid spraying profilesaccording to the operation of FIG. 6 in one or more embodiments.

FIG. 8 illustrates a graph of a spraying profile adjustment during aliquid dispensing process, in accordance with an embodiment.

FIGS. 9A and 9B illustrate two alternative liquid dispensing apparatus,in accordance with various embodiments of the present disclosure.

FIG. 10 illustrates a flow chart of a liquid dispensing method accordingto various aspects of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The present disclosure in various embodiments is generally related to anozzle and a method for dispensing liquids onto a surface. Moreparticularly, the present disclosure relates to a fluid dispensingnozzle and method for dispensing process liquids, such as photoresistand developer chemicals, onto a rotating semiconductor substrate. In thepresent disclosure, the terms “process liquid,” “liquid coatingmaterial,” and “chemical fluid” are used interchangeably.

In manufacturing integrated circuits (IC), a lithography process is usedfor reproducing layers to form structures on a semiconductor substrate.In some embodiments, as a first step in a lithography process, aphotoresist layer is coated onto a semiconductor substrate such that animage can be projected and developed thereon. The photoresist materialis a liquid that is coated as a thin layer on top of the substrate. Invarious processes for applying a photoresist coating material to asubstrate, a spin dispensing apparatus is normally used. The spindispensing apparatus includes a nozzle to spray the liquid coatingmaterial from an orifice of the nozzle towards the substrate, and thesubstrate is spun so that a uniform coating remains on the substrate.One or more materials may be so dispensed and coat the substrate. Thebackside of the substrate is rinsed, and the coating material is removedfrom an edge of the substrate. The coating is allowed to dry before itis soft-baked to solidify. An image pattern is then projected onto thephotoresist material.

In the developing process, a spin dispensing apparatus is also used. Thephotoresist material can be either negative tone or positive tone.Regardless of the type of photoresist material, the developer solutiondissolves or chemically changes either the exposed portion or unexposedportion of the photoresist material. The developer solution may bedispensed over the substrate in a scan pattern while the substratespins. Once the chemical reaction takes place, the substrate is rinsedto remove a portion of the photoresist material. The resulting coatpattern is baked to harden and may be used as a mask for an etch step ora deposition step to form a subsequent layer on the substrate.

As the feature sizes decrease for integrated circuits, the quality ofthe coating and developing becomes more important. Defects may formduring the dispensing operations of the coating and/or developingprocesses. Therefore, improved dispensing apparatus and methods continueto be sought. Depending on the user's applications, some variables toconsider in designing a dispensing apparatus include: the separationdistance from a nozzle to a substrate thereunder, a rotational speed ofa substrate during dispense, a rate of translation of a dispenser arm,fluid temperatures, substrate temperatures, dispensing flow rates, andthe rheology of dispensed fluids. Nonetheless, bores and orifices ofdispensing nozzles normally have fixed circular cross-sections, out of ascope of tunable variables for optimizing coating and developingprocesses. The present disclosure provides a dispensing nozzle withadjustable cross-sections. Thus, the shapes and dimensions of the nozzlebores and orifices are adjustable upon applications.

FIG. 1 is a schematic of a spin dispensing apparatus 100 in accordancewith various embodiments of the present disclosure. The spin dispensingapparatus 100 includes a circular-shaped, rotatable platform 102 thathas a diameter smaller than the diameter of a semiconductor substrate104. The rotatable platform 102 is positioned in a cup 106 and includesa vacuum chuck 108—vacuum is applied to the platform to hold thesemiconductor substrate 104 securely during a spin process. Therotatable platform 102 is positioned in the spin dispensing apparatus100 such that a semiconductor substrate 104 may be placed on tophorizontally. During the coating process, the bottom or uncoated surfaceof the semiconductor substrate 104 contacts the vacuum chuck 108. Asuitable vacuum is applied to the bottom surface of the semiconductorsubstrate 104 such that it stays securely on the vacuum chuck 108 athigh rotational speeds. The rotating motion of the vacuum chuck 108 isachieved by a shaft 110, which is connected to the vacuum chuck 102 andpowered by a motor. The motor is capable of rotating the vacuum chuck atdifferent speeds. The cup 106 includes one or more exhausts to whichexcess liquid coating material flows. The spin dispensing apparatus 100also includes a dispensing nozzle 120 disposed above the rotatableplatform 102. Though a delivery conduit 121, the dispensing nozzle 120is coupled to a liquid coating material source (or fluid source) 122that supplies a chemical fluid 124, which may be a photoresist material,a developer, or some other suitable chemical fluids to be dispensed ontoand coat the substrate 104. The dispensing nozzle 120 includes anorifice 126 through which the chemical fluid 124 flows. A gas sprayer130 is also disposed in a proximity region of the orifice 126 andconnected to a gas source (not shown) that provides an inert gas 132,which may be nitrogen, helium, argon, or some other suitable inertgases. The inert gas 132 is sprayed laterally towards the orifice 126,which increases an ambient pressure surrounding the chemical fluid 124that is being sprayed away from the orifice 126. The gas sprayer 130 mayuse a nozzle as a gas outlet. In that regard, the gas sprayer 130 mayalso be referred to as the gas outlet nozzle 130. As will be explainedin further detail below, by adjusting an ambient pressure in theproximity region of the orifice 126, a conical spraying profile 134 ofthe chemical fluid leaving the orifice 126 can be fine-tuned, therebyincreasing or decreasing a spraying area on the beneath semiconductorsubstrate 104. The dispensing nozzle 120 is further attached to adispenser arm 140, which is operable to move in a vertical direction 142or in a horizontal direction 144. Hence, the dispensing nozzle 120 canbe moved to a center region or other peripheral regions above thesemiconductor substrate 104. Similarly, a vertical distance from theorifice 126 to the semiconductor substrate 104 can be adjusted by thedispenser arm 140. The vertical distance also affects chemical fluidmomentum and spraying area on the semiconductor substrate 104.

One use of a spin dispensing apparatus 100 is to coat a photoresistmaterial on a substrate. In a photoresist coating process in accordancewith various embodiments of the present disclosure, a desirable amountof a liquid photoresist material is applied to a top surface of thesemiconductor substrate 104 from the liquid dispensing nozzle 120 as thevacuum chuck 108 spins. The photoresist liquid spreads radially outwardfrom a location of the semiconductor substrate 104 where the liquidlands towards the edge until the entire top surface of the semiconductorsubstrate 104 is covered with a thin layer. Excess photoresist liquidspins off the rotating substrate during the photoresist coating process.The rotational speed of the vacuum chuck and the amount of thephotoresist liquid applied can be determined and adjusted prior to andduring an application process such that a predetermined, desirablethickness of the photoresist is obtained.

Another use of a spin dispensing apparatus 100 is to develop exposedphoto resist material on a substrate. After a photoresist layer isformed, the semiconductor substrate 104 is exposed to a patterned lightthat affects the chemical properties of the photoresist. When a positivephotoresist is used, a portion of the photoresist that is exposed tolight becomes soluble to a photoresist developer. When a negativephotoresist is used, a portion of the photoresist that is not exposed tolight becomes soluble to a photoresist developer. The spin dispensingapparatus 100 may be used to apply a developer to the semiconductorsubstrate 104. A dispenser arm 140 is mounted on a track while thevacuum chuck 108 is rotated at a dispensing speed. The dispensing nozzle120 may scan the substrate to ensure even distribution of the developer.The developer and the photoresist are given time to react and then adissolved portion of the photoresist layer is removed by rinsing. Thesemiconductor substrate 104 is then dried. Other uses of a spindispensing apparatus 100 may include, but not limited to, dispensingrinsing chemical in a rinsing process or dispensing slurry in achemical-mechanical polishing (CMP) process.

FIG. 2 shows a cross-sectional view of the dispensing nozzle 120. Thedispensing nozzle 120 has a sidewall 202. A central bore 204 is definedwithin the sidewall 202, which is axisymmetric about a longitudinal axisA-A. The dispensing nozzle 120 is in fluid communication with a fluidsource 122 (as shown in FIG. 1 ). The chemical fluid 124 from the fluidsource 122 is pumped into the bore 204 from above and flows downwardlytowards the orifice 206. The chemical fluid 124 is subsequently sprayedaway through the orifice 206 towards a beneath substrate 104 (as shownin FIG. 1 ). In some embodiments, the dispensing nozzle 120 furtherincludes a gas sprayer 240 in a proximity region of the orifice 206,which is operable to spray an inert gas 242 laterally towards theorifice 206. The inert gas 242 may include nitrogen, helium, argon,other suitable inert gas, or a combination thereof, such that it doesnot involve in chemical reactions with the chemical fluid 124. Sprayingan inert gas towards the orifice 206 increases the ambient pressuresurrounding the orifice 206. The directions of chemical fluid dropletsspraying away from the orifice 206 may be influenced by the ambientpressure. The inventors of the present disclosure have observed thatextra ambient pressure added to a region surrounding the orifice 206leads to an expanded spraying profile, and vice versa. Therefore, aspraying area on the beneath substrate 104 can be adjusted by varyingthe inert gas flow rate from the gas sprayer 240.

The cross-section of the bore 204 (including the orifice 206) also hasimpacts on fluid dynamics of the chemical fluid 124, including innerpressure, flow rate, and spraying profile. It is advantageous for thedispensing nozzle 120 to be operable to adjust cross-section of the bore204 beforehand based on material compositions of the chemical fluid 124and dispensing application requirements, or even to further adjustcross-section on-the-fly during a dispensing operation.

In the illustrated embodiment, the sidewall 202 has an inner layer 208and an outer layer 210. The inner layer 208 directly faces the bore 204.A cavity 212 is defined between the inner layer 208 and the outer layer210. The cavity 212 is elsewhere sealed by the inner and outer layersbut has an inlet 214 opened to an inflation tube 216. Both inner andouter layers 208, 210 are made of elastic materials, such as elasticplastic films. The elastic materials can be stretched or compressed dueto external forces. The inflation tube 216 is coupled to a gas pump (notshown) that provides a gas 218. In some embodiments, the gas 218includes an inert gas, such as nitrogen, helium, argon, other suitablegases, or a combination thereof. In some embodiments, the gas 218 isair. When the gas 218 is pumped into the cavity 212, the cavity 212starts to inflate. The inflation forces both the outer layer 210 and theinner layer 208 to expand in a direction away from the longitudinal axisA-A. The outer layer 210 travels in a longer lateral distance than theinner layer 208, effectively enlarging the inflated cavity 212 toaccommodate the gas 218. The inner layer 208 travels in a shorterlateral distance than the outer layer 210, while its expansionnonetheless enlarges the bore 204.

In some embodiments, the inner and outer layers 208, 210 are plasticfilms made of fluorinated ethylene propylene (FEP). FEP is achemically-resistant material that is not wettable by the fluid beingdispensed, which reduces the likelihood of a post-dispense dripping. FEPfurther has good stability and a high flow rate for injection molding.Alternatively, polytetrafluoroethylene (PTFE) or Perfluoroalkoxy alkanes(PFA) may be used. Both of these materials are chemically inert to mostindustrial chemicals and solvents. The above-mentioned plastics are alsoeasily molded, yielding smooth molded surfaces for better fluid flow. Inone embodiment, the inner and outer layers 208, 210 have differentmaterial compositions. For example, the inner layer 208 is made of anFEP film and the outer layer 210 is made of a PTFE film.

Still referring to FIG. 2 , the dispensing nozzle 120 further includes aplurality of pins 220. Depending on a vertical distance to the orifice206, the plurality of pins 220 can be grouped into a stack of multiplelayers, where each layer includes the pins at the same vertical distanceto the orifice 206. In some embodiments, the pin 220 has a rod shapeelongating in a lateral direction perpendicular to the longitudinal axisA-A. Each pin 220 is also movable in the lateral direction perpendicularto the longitudinal axis A-A, along a groove 222 opened in a housing224. In one embodiment, the movement of the pin 220 along the groove 222is driven by a mechanism in physical contact with one end of the pin,such as a piston (not shown). In the illustrated embodiment, themovement of the pin 220 is controlled by adding gaseous pressure 226through an open end of the groove 222. All the grooves 222 are coupledto a gas pump (not shown), which provides a gas to be blown towards thepins 220. In some embodiments, the gas blown towards the pins 220includes an inert gas, such as nitrogen, helium, argon, other suitablegases, or a combination thereof. In some embodiments, the gas blowntowards the pins 220 is air. Each groove 222 also has a valve (notshown) to control the gaseous pressure 226 inside the respective groove222. The pressure 226 drives the pin 220 to move towards andsubsequently in physical contact with the outer layer 210. In otherwords, the positions of the tips of the pins 220 define a contour forthe outer layer 210 to fit in, which in turn defines a cross-section ofthe inner layer 208 and thereby a cross-section of the bore 204. Byincreasing the gaseous pressure 226, the pins 220 move further towardsthe center of the bore 204 and shrink the cross-section of the bore 204.On the other hand, by decreasing the gaseous pressure 226 inside thegroove 222, the expansion force from the outer layer 210 will outweighthe gaseous pressure 226 and push back the pin 220 until reaching a newbalance position between opposite forces—inflation force and compressionforce. In this way, the contour defined by the pins 220 is expanded andso does the cross-section of the bore 204. In some embodiments, the gaspump coupled to the grooves 222 can switch to become a suction pumpwhich creates a negative pressure inside the grooves 222 and withdrawsthe pins 220 away from the bore 204.

FIG. 3A shows cross-sectional view along B-B line of FIG. 2 , which isperpendicular to the longitudinal axis A-A of the dispensing nozzle 120.The pins 220 in the same layer (i.e., with the same vertical distance tothe orifice 206 shown in FIG. 2 ) are allocating along a circumferenceof the bore 204. The pins 220 are embedded in the housing 224 and drivenby the gaseous pressure 226 to slide in respective grooves. By tuningthe gaseous pressure 226, each pin 220 is adjusted to a predeterminedposition, such as forming a circular contour as illustrated in FIG. 3A.Simultaneously, the cavity 212 sealed between the inner layer 208 andthe outer layer 210 is inflated by a gas, which causes both sidewalls208, 210 to expand towards the pins 220 and subsequently confined by thecircular contour, thereby forming the bore 204 with a cross-sectionsubstantially similar to the contour (e.g., a circular shape). FIGS. 3Band 3C illustrates other shapes, such as a triangle (FIG. 3B) and asquare (FIG. 3C), to which the bore 204 can be adjusted. In variousembodiments, a cross-section of the bore 204 may be of any shape, suchas square, rectangular, circular, oval, polygonal, or even irregularshapes.

As illustrated in FIG. 3B, to form a determined shape, it is notnecessary for all the pins 220 to be in physical contact with the outerlayer 210 to form a contour. In FIG. 3B, the pins 220 a-e do notparticipate in forming a contour, therefore these pins can be withdrawnfrom contacting with the outer layer 210 by applying a suction force tothe other end of the respective pins. FIGS. 3C and 3D further illustratethe cross-sectional area of the bore 204 can be increased or decreasedwhile maintaining the same shape (e.g., the illustrated square shape,but not limited to). It is beneficial to vary a cross-sectional area ofthe bore 204 for dispensing. Smaller the cross-sectional area, strongerthe fluid pressure inside the bore 204, which facilitates spraying achemical fluid with a high viscosity. On the other hand, larger thecross-sectional area, weaker the fluid pressure inside the bore 204,which reduces the likelihood of a post-dispense dripping or furtherfacilitates a “suckback” operation at the tip of the nozzle. “Suckback”is a term used to describe the procedure of chemical fluid slightlywithdrawn from the orifice at the conclusion of the fluid dispense toreduce unwanted fluid drops. Varying cross-sectional area can beachieved by moving the pins 220 all-together forward or backward withrespect to the outer layer 210.

Referring back to FIG. 2 , in some embodiments, each of the inflationtube 216, the grooves 222, and the gas sprayer 240 may be coupled to thesame gas pump (not shown) but with a separate gas valve to control eachrespective gas communication path, since they all may use the same inertgas. In some other embodiments, the inflation tube 216 and the grooves222 share the same gas pump, while the gas sprayer 240 is using aseparate gas pump providing a different gas composition.

FIG. 2 also illustrates an enlarged region 230 proximate to two adjacentpins 220. In some embodiments, the pin 220 is a rod with a lengthranging from about 1 mm to about 20 mm and a cross-sectional diameter dless than the length, such as about 2 mm. The two adjacent pins 220 havea pitch p. Since the outer and inner layers 208, 210 are made of elasticmaterial, the outer layer 210 may have a convex portion expanded into aspace between the two adjacent pins 220. Consequently, the inner layer208 will also have a convex portion. Two imaginary vertical lines 232and 234 parallel to the longitudinal axis A-A are added to contrast withthe convex portions of the inner and outer layers 208, 210. From top tobottom, there would be a series of convex portions along both the innerand outer layers 208, 210. The convex portions of the inner layer 208are more sensitive in affecting a smooth fluid flow than the ones of theouter layer 210. To mitigate the impact of the convex portions, theinner layer 208 may have a larger thickness than the outer layer 210,such as about 20% to about 50% thicker, which makes the inner layer 208more rigid. In some embodiments, the inner layer 208 is made of a lesselastic material than the outer layer 210. Alternatively, smaller pitchp of the pins 220 can also mitigate the convex portions but with a costof adding more pins and increasing system complexity. The inventors ofthe present disclosure have discovered that a ratio of p over d in arange from about 2:1 to about 5:1 provides a reasonable balance formitigating impacts of convex portions and keeping relatively low systemcomplexity.

FIGS. 4A and 4B illustrate a cross-sectional view along the longitudinalaxis A-A of the dispensing nozzle 120 with a tapered sidewall 202. Insome embodiments, the tapered sidewall 202 form an angle with respect tothe top surface of the beneath spinning substrate in a range from about50 degrees to about 130 degrees, such as about 85 degrees in a specificexample. With the tapered sidewall 202, the cross-sectional area of thebore 204 at different vertical distance from the orifice 206 varies,similar to a funnel. The cross-sectional area of the bore 204 maygradually shrink towards the orifice 206 (FIG. 4A), which increasesfluid pressure to accelerate dispensing velocity. Alternatively, thecross-sectional area of the bore 204 may gradually enlarge towards theorifice 206 (FIG. 4B), which reduces fluid pressure to slow downdispensing velocity and facilitate “suckback” operation. To form thetapered sidewall 202, the gaseous pressure 226 varies in a gradient fromtop to bottom, causing the pins 220 in different stacked layers toextrude different distances towards the outer layer 210. The tips of thepins 220 form a contour that has a tapered profile for the outer layer210 to fit in. In some embodiments, the gaseous pressure 226 applied tothe topmost pin 220 is about 20 psi, and the gaseous pressure 226applied to the bottommost pin 220 is about 100 psi (FIG. 4A), or viceversa (FIG. 4B).

In one alternative embodiment, the sidewall 202 includes a single layerinstead of the inner and outer double layers. The single layer is madeof elastic material, such as an elastic plastic film. The single layerin its natural stretching out conditions will expand beyond the contourline when all pins 220 have been withdrawn into the grooves 222.Therefore, there is no need for using an inflation tube 216 to expandthe sidewall 202, as the elastic material always has the tendency toexpand itself. Similar to what has been discussed above, to definecross-section of the bore 204, the pins 220 driven by the gaseouspressure 226 to push back the sidewall 202 to a determined position,where expansion force and compression force achieve at a balance at thatposition. The tips of the pins 220 in the stacked layers collectivelydefine a cross-section profile of the bore 204.

FIG. 5 is a flow chart of a method 500 of dispensing chemical fluids ina semiconductor device fabrication process using a spin dispensingapparatus, such as the spin dispensing apparatus 100 illustrated in FIG.1 , according to various aspects of the present disclosure. Additionaloperations can be provided before, during, and after the method 500, andsome operations described can be replaced, eliminated, or relocated foradditional embodiments of the method. The method 500 is an example, andis not intended to limit the present disclosure beyond what isexplicitly recited in the claims.

The method 500 begins at operation 502 where a substrate is provided.The substrate may be a semiconductor wafer. In an embodiment, thesubstrate is a 450 mm diameter semiconductor wafer. The substrateprovided may be substantially similar to the semiconductor substrate104, discussed above with reference to FIG. 1 . The substrate may beprovided to a stage of a spin dispensing apparatus, such as, forexample, described above with reference to the vacuum chuck 108.

The method 500 then proceeds to operation 504 where a dispensing nozzleis positioned above the substrate. The dispensing nozzle may besubstantially similar to the dispensing nozzle 120, discussed above withreference to FIG. 1 . FIG. 1 illustrates the nozzle 120 being attachedto a dispenser arm 140. The dispenser arm 140 is operable to movevertically or laterally. In some embodiments, either a translational ora rotational dispense arm sweep trajectory, or a combination thereof,may be used during a dispensing process. The nozzle 120 may be positionabove the center or above the edge of the substrate. The separationdistance between the nozzle and the substrate affects momentum of thechemical fluid droplet arriving at the substrate surface. Larger thedistance, stronger the momentum and larger the spraying area, and viceversa. In some embodiments, the separation may be less than about 150mm, for example about 5 mm to about 20 mm, for suitable momentumadjustment of the dispensed chemical fluid.

The method 500 then proceeds to operation 506 where a cross-sectionprofile of the nozzle fluid path, such as the bore 204 illustrated inFIG. 2 , is determined for the dispensing process. The cross-sectionprofile determined may include one or more geometrical parameters, suchas a shape of the cross-section, a size of the cross-section,substantially vertical or tapered sidewalls of the bore, and acombination thereof. Consideration for determining the cross-sectionprofile may include the chemical fluid compositions to be delivered toand dispersed by the nozzle, the concentration of the chemical fluid,the flow rate of the chemical fluid, the temperature of the chemicalfluid, the physical location of the nozzle with respect to thesubstrate, targeted coating thickness, spinning speed or spinningprofile of the shaft, and/or other recipe parameters. In one embodiment,the cross-section of the bore 204 has an oblong shape with roundedcorners. In another embodiment, the cross-section of the bore 204 has asquare shape with an area tapering down from top to bottom towards theorifice 206. In yet another embodiment, the cross-section of a topportion of the bore 204 starts with a square shape but graduallytransits into a circular shape at a bottom portion of the bore 204.

The method 500 then proceeds to operation 508 where the determinedcross-section profile is applied to the nozzle. The nozzle has a housingcontaining a plurality of movable pins substantially similar to the pins220, discussed above with reference to FIG. 2 . The movable pins eachcan be driven forward or backward by a gas pressure controlled by a gasvalve coupled to a gas pump. Tips of the movable pins define a contour,which corresponds to a shape and area determined in the cross-sectionprofile settings. The sidewall of the nozzle is made of elastic materialwhich can be expanded outwardly, such as by pumping in gas, similar toinflate a balloon. The expanding sidewall of the nozzle subsequentlycomes into physical contacts with the tips of the movable pins and fitin the contour, such that the bore 204 is configured to have thedetermined cross-section profile.

The method 500 then proceeds to operation 510 where chemical fluid isdispensed to the substrate according to the determined profile set forthe nozzle. Example chemical fluid compositions include those chemicalsoften found used in semiconductor fabrication such as, DI, SC₁ (DI,NH₄OH, H₂O₂), SC₂ (DI, HCl, H₂O₂), ozonated de-ionized water (DIWO₃),SPM (H₂SO₄, H₂O₂), SOM (H₂SO₄, O₃), SPOM, H₃PO₄, dilute hydrofluoricacid (DHF), HF, HF/EG, HF/HNO₃, NH₄OH, tetramethylammonium hydroxide(TMAH) or other photosensitive material developer, and/or other suitablechemicals used in semiconductor wafer processing. Example flow ratesinclude those between about 50 sccm and about 5,000 sccm. In someembodiments, the nozzle is held above the spin axis of the wafersubstrate, and the chemical fluid is dispensed from the nozzle onto thespin wafer substrate. Once the wafer substrate is flooded with thechemical fluid, it is rapidly accelerated to a predetermined spin speedto spread the chemical fluid into a uniform film at the wantedthickness.

While chemical fluid is being dispensed to the substrate, the method 500proceeds to operation 512 to adjust ambient pressure in a proximateregion of the nozzle by using a gas sprayer. The gas sprayer may besubstantially similar to the gas sprayer 240, discussed above withreference to FIG. 2 . The gas sprayer is connected to a gas source thatprovides an inert gas, such as nitrogen, helium, argon, other suitableinert gases, or a combination thereof. The inert gas is sprayed towardsthe orifice of the nozzle, which increases an ambient pressuresurrounding the chemical fluid dispensed away from the orifice. Thechange of the ambient pressure in the proximity region of the orificehas a direct impact on the conical spraying profile of the chemicalfluid droplets leaving the orifice, which in turn varies coverage of aspraying area on the beneath substrate. In some embodiments, operation512 is optional and can be skipped.

Operation 512 may include multiple steps. FIG. 6 shows an embodiment ofoperation 512 implemented with the spin dispensing apparatus 100illustrated in FIGS. 7A-7C. Referring to FIG. 6 , operation 512 includesa step 608, which determines a set of gaseous pressure and correspondingtiming for a gas sprayer 240 to apply in a proximity region of theorifice 126 of the nozzle 120; and a step 610, which adjusts the gassprayer 240 with the determined set of gaseous pressure andcorresponding timing in sequence on-the-fly with the chemical fluidbeing dispensed. Referring to FIGS. 7A-7C, one difference between FIGS.7A, 7B, and 7C is the amount and velocity of the gas 242 sprayed awayfrom the gas sprayer 240, which can be quantified by measuring extragaseous pressure applied to ambient environment surrounding the orifice126. A graph 810 in FIG. 8 illustrates that the applied gaseous pressureby the gas sprayer 240 is a function of time (i.e., it is not constant,and it may vary over time or during some periods of time) during thestep 610, in accordance with an embodiment. Referring to the graph 810,the step 610 includes a 3-stage flexible adjustment in the illustratedembodiment. The three stages are labeled as P₁, P₂, and P₃, which arealso the value to the gaseous pressure applied to the ambientenvironment surrounding the orifice 126 at each respective stage. Withineach stage, the gaseous pressure remains substantially constant. Fromone stage to a subsequent (the immediately next) stage, the gaseouspressure varies. The three gaseous pressures P₁, P₂, and P₃ may be alldifferent, or some of them may be the same. In an embodiment, it mayhold true that P₁≠P₂ and P₂≠P₃, but P₁=P₃. Further, the graph 810 shownin FIG. 8 is merely an example of the flexible adjustment of the gassprayer 240. The various gas pressures and durations may be modifiedand/or removed, and additional gas pressures and durations may be addedor inserted for additional embodiments.

For example, in the illustrated embodiment of the graph 810 shown inFIG. 8 , the three gas pressures P₁, P₂, and P₃ have the relationship ofP₁<P₂<P₃, which associates with the dispensing status shown respectivelyin FIGS. 7A-7C. In FIG. 7A, the gas sprayer 240 shuts off gas supply(e.g., by a gas valve) and has no spray of inert gas 242 towards theorifice 126. Therefore, there is no extra gaseous pressure (P₁=0) addedto the ambient environment of the orifice 126. If the orifice 126 is setto a circular cross-section by the nozzle 120, the chemical fluidsprayed away from the orifice 126 may have a conical spraying profile134. In one embodiment, the spraying profile 134 is a cylindrical shape.In yet another embodiment, the spraying profile 134 is a funnel shape.Corresponding to the spraying profile 134, a region under the orifice126 on the top surface of the substrate 104 is wet by the dispensedchemical fluid, which is termed spraying area. In FIG. 7A, the sprayingarea has a diameter d₁. The inventors of the present disclosure havediscovered that by increasing ambient pressure the spraying profile 134will expand outwardly. In FIG. 7B, the gas sprayer 240 sprays the inertgas 242 towards the orifice 126 (e.g., by turning on a gas valve) andthereby adding an extra gaseous pressure (P₂>P₁) to the ambientenvironment of the orifice 126. The increasing ambient pressure causesthe chemical fluid to spray away further outwardly from the center ofthe orifice 126 and results in an expanded spraying profile 134. Thecorresponding spraying area on the substrate 104 covered by the sprayingprofile 134 is also enlarged with an increased diameter d₂ (d₂>d₁). InFIG. 7C, the gas sprayer 240 sprays more inert gas 242 with a higherflow rate and momentum towards the orifice 126 (e.g., by fully opening agas valve) and thereby adding more gaseous pressure (P₃>P₂>P₁) to theambient environment of the orifice 126. Similarly, the increasingambient pressure causes the chemical fluid to spray outwardly evenfurther from the center of the orifice 126 and results in a furtherexpanded spraying profile 134. The corresponding spraying area on thesubstrate 104 covered by the spraying profile 134 is also enlarged withan increased diameter d₃ (d₃>d₂>d₁). In some embodiments, when the addedgaseous pressure exceeds certain amount, the spraying profile 134 maybecome a conical ring with few chemicals dispensed directly under theorifice 126, and the spraying area on the substrate 104 becomes acircular ring instead of a circle consequently. Generally, as a resultof increasing extra ambient pressure from P₁ to P₃, wider area away fromthe center of the substrate 104 is wet directly from the dispensedchemical fluid. Compared with other methods by first accumulating excessamount of chemical fluid in a center region then spinning it toperipheral regions, step 610 wets peripheral regions directly during adispensing process, which increases operation efficiency and reducesfluid waste during a following spinning process.

Referring back to FIG. 5 , while chemical fluid is being dispensed tothe substrate, the method 500 may optionally proceed to operations 514and 516. In some embodiments, operations 514 and 516 can be skipped.Operation 514 is substantially similar to operation 506, where a newcross-section profile of the nozzle fluid path is determined for thecontinuing dispensing process. Operation 516 is substantially similar tooperation 508, where the determined new cross-section profile is appliedto the nozzle by adjusting positions of movable pins. For example, inone embodiment, the dispensing process starts with a circular shapeorifice and transits into a rectangular shape orifice on-the-fly duringdispensing when temporally close to an end of the dispensing process,which may help reducing the likelihood of a post-dispense dripping.Similarly, operations 514 and 516 may keep a cross-sectional shape ofthe fluid path but change its size on-the-fly during dispensing. Forexample, the dispensing process may start with a rectangular shapeorifice (e.g., FIG. 3D) and gradually enlarge the cross-sectional area(e.g., FIG. 3C) while an extra gaseous pressure is being added by a gassprayer to the ambient environment of the orifice, which may facilitateexpanding spraying area on the beneath substrate.

Another embodiment of a dispensing nozzle is illustrated in FIG. 9A. Asshown in FIG. 9A, the dispensing nozzle 900 includes a delivery conduit902 coupled to a fluid source (not shown) that supplies a chemical fluid930. The dispensing nozzle 900 also includes a dispensing outlet 904.The dispensing outlet 904 includes two or more orifices 906 withdifferent cross-section profile. In the illustrated embodiment in FIG.9A, the dispensing outlet 904 includes three orifices 906 a, 906 b, and906 c with different cross-sectional shapes, such as a square, a circle,and a triangle, respectively. In various embodiments, each orifice 906may individually be of any shape, such as square, rectangular, circular,oval, polygonal, or even irregular shapes. In some embodiments, eachorifice 906 may have the same cross-sectional shape but vary in sizes.Each orifice 906 connects to a branch tube 908 (e.g., tubes 908 a, 908b, or 908 c). All the branch tubes 908 merge into a main tube 910. Themain tube 910 directly couples to the delivery conduit 902. Each orifice906 further associates with an adjustable flow control valve 912 (e.g.,valves 912 a, 912 b, or 912 c) installed on respective branch tube 908.The flow control valve 912 controls which orifice to establish a fluidcommunication path with the delivery conduit 902. For example, in theillustrated embodiment in FIG. 9A, when the flow control valve 912 a and912 b are close and the flow control valve 912 c is remained open, thechemical fluid 930 flows through the delivery conduit 902, then entersthe branch tube 908 c, and is subsequently sprayed away from thetriangular orifice 906 c. Similarly, orifices 906 a and 906 b may beindividually selected for other dispensing applications. The dispensingnozzle 900 may further include a gas sprayer 920 in a proximity regionof the orifices 906. The gas sprayer 920 is operable to spray an inertgas to increase an ambient pressure surrounding the orifices 906, whichadjusts a spraying profile from the dispensing nozzle 900.

Yet another embodiment of a dispensing nozzle is illustrated in FIG. 9B.Similar to the dispensing nozzle shown in FIG. 9A, the dispensing nozzle900 in FIG. 9B includes a delivery conduit 902 coupled to a fluid source(not shown) that supplies a chemical fluid 930. The dispensing nozzle900 also includes a dispensing outlet 904. The dispensing outlet 904includes two or more orifices 906 with different cross-section profile.In the illustrated embodiment in FIG. 9B, the dispensing outlet includesthree orifices 906 a, 906 b, and 906 c with different cross-sectionalshapes, such as a square, a circle, and a triangle, respectively. Invarious embodiments, each orifice 906 may individually be of any shape,such as square, rectangular, circular, oval, polygonal, or evenirregular shapes. In some embodiments, each orifice 906 may have thesame cross-sectional shape but vary in sizes. Each orifice 906 connectsto one end of a branch tube 908 (e.g., tubes 908 a, 908 b, or 908 c). Onthe other end of the branch tube 908 is an inlet adapter 928 (e.g.,inlet adapters 928 a, 928 b, or 928 c). Without using flow controlvalves in branch tubes to establish a fluid communication path, thedelivery conduit 902 is attached to a movable mechanism, such as arobotic arm, a slider, or a rail, which is operable to move the deliveryconduit 902 along a direction 940 to above a selected inlet adapter 928for latching. Once the delivery conduit 902 is physically latched to theselected inlet adapter 928, a fluid communication path is establishedfor the chemical fluid 930 to flow through the delivery conduit 902 tothe latched branch tube 908, and subsequently to spray from thecorresponding orifice 906. The dispensing nozzle 900 may further includea gas sprayer 920 in a proximity region of the orifices 906. The gassprayer 920 is operable to spray an inert gas to increase an ambientpressure surrounding the orifices 906, which adjusts a spraying profileof the dispensing nozzle 900.

FIG. 10 is a flow chart of a method 1000 of dispensing chemical fluidsin a semiconductor device fabrication process using a dispensingapparatus, such as the dispensing nozzle 900 illustrated in FIG. 9A orFIG. 9B, according to various aspects of the present disclosure.Additional operations can be provided before, during, and after themethod 1000, and some operations described can be replaced, eliminated,or relocated for additional embodiments of the method. The method 1000is an example, and is not intended to limit the present disclosurebeyond what is explicitly recited in the claims.

The method 1000 begins at operation 1002 where a substrate is provided.The substrate may be a semiconductor wafer. In an embodiment, thesubstrate is a 450 mm diameter semiconductor wafer. The substrateprovided may be substantially similar to the semiconductor substrate104, discussed above with reference to FIG. 1 . The substrate may beprovided to a stage of a spin dispensing apparatus, such as, forexample, described above with reference to the vacuum chuck 108. Themethod 1000 then proceeds to operation 1004 where a dispensing nozzle ispositioned above the substrate. The dispensing nozzle may besubstantially similar to the dispensing nozzle 900 in either FIG. 9A orFIG. 9B. The dispensing nozzle 900 includes a dispensing outlet 904which has two or more orifices 906. The orifices 906 vary incross-sections, such as in different cross-sectional shapes or differentcross-sectional areas. Each orifice is suitable for one specificdispensing recipe. The method 1000 then proceeds to operation 1006 whereone of the orifices 906 (e.g., orifice 906 a, 906 b, or 906 c) is pickedfor establishing a fluid communication path. The fluid communicationpath may be established by using fluid control valves to shut off branchpaths to other orifices (e.g., as shown in FIG. 9A) or by physicallyconnecting a movable delivery conduit 902 to one of the inlet adapters928 (e.g., inlet adapter 928 a, 928 b, or 928 c) corresponding to theselected orifice (e.g., as shown in FIG. 9B). The method 1000 thenproceeds to operation 1008 where chemical fluid is dispensed to thesubstrate through the established fluid communication path. In someembodiments, the chemical fluid 930 is a photoresist or a photoresistdeveloper used in a photolithography process. In some embodiments, thechemical fluid 930 is a rinsing chemical used in a rinsing process or aslurry used in a CMP process.

Although not intended to be limiting, one or more embodiments of thepresent disclosure provide many benefits to liquid dispensing processes.For example, embodiments of the present disclosure are capable ofadjusting cross-sectional shapes and dimensions of dispensing nozzlebores and orifices upon dispensing recipes. This greatly increasesdispensing flexibility and improves coating uniformity across the wafer.In addition, embodiments of the present disclosure enable flexibledispensing system designs and reduce chemical fluid waste.

In one exemplary aspect, the present disclosure is directed to anapparatus for dispensing fluid. The apparatus includes a fluid source; anozzle having an inner layer and an outer layer, the inner layerdefining a bore in fluid communication with the fluid source; and aplurality of pins each movable to be in physical contact with the outerlayer, wherein the plurality of pins is operable to apply a forcetowards the outer layer to adjust a cross-section of the bore. In someembodiments, each of the plurality of pins is movable in a directionperpendicular to a longitudinal axis of the bore. In some embodiments,each of the plurality of pins is movable by applying a gaseous pressure.In some embodiments, the inner and outer layers are made of elasticmaterial. In some embodiments, the elastic material of the inner layeris more rigid than that of the outer layer. In some embodiments, theinner and outer layers form a cavity that can be inflated by pumping ingas. In some embodiments, the cross-section of the bore is adjustable tovary in shapes. In some embodiments, the shapes are selected fromtriangle, rectangle, square, circle, oval, and polygon. In someembodiments, the cross-section of the bore is adjustable to vary incross-sectional areas along a longitudinal axis of the bore. In someembodiments, the apparatus also includes a gas outlet nozzle in aproximity region of an orifice of the nozzle, wherein the gas outletnozzle is operable to increase an ambient pressure in the proximityregion. In some embodiments, the apparatus also includes a movable armattached to the nozzle, the movable arm being operable to move thenozzle horizontally and vertically. In some embodiments, the apparatusalso includes a rotatable platform to hold and rotate a substrate tocoat with the fluid dispensed from the nozzle.

In another exemplary aspect, the present disclosure is directed to anapparatus for semiconductor manufacturing. The apparatus includes awafer chuck; a dispensing outlet positioned above the wafer chuck,wherein the dispensing outlet includes at least two orifices, eachorifice having a different cross-sectional shape; a delivery conduitcoupled to a fluid source, wherein the delivery conduit is operable tocouple with one of the at least two orifices for fluid communication;and a gas sprayer in a proximity region of the at least two orifices,wherein the gas sprayer is operable to spray a gas to increase anambient pressure in the proximity region. In some embodiments, eachorifice is controlled by an adjustable flow control valve. In someembodiments, each orifice has a corresponding inlet adapter tomechanically latch to the delivery conduit. In some embodiments, theapparatus also includes a movable mechanism attached to the deliveryconduit, the movable mechanism is operable to move the delivery conduitwith reference to the dispensing outlet. In some embodiments, the atleast two orifices include at least one orifice with a triangularcross-section. In some embodiments, the gas sprayer is operable to varya flow rate of the gas during a dispensing operation.

In another exemplary aspect, the present disclosure is directed to amethod of dispensing fluid. The method includes providing a substrate;positioning a nozzle above the substrate; determining a cross-sectionalshape of the nozzle; configuring the nozzle to have the determinedcross-sectional shape; and applying a fluid to the substrate through thenozzle with the determined cross-sectional shape. In some embodiments,the method also includes determining a different cross-sectional shapeof the nozzle; and configuring the nozzle to have the determineddifferent cross-sectional shape during the applying of the fluid to thesubstrate.

The foregoing outlines features of several embodiments so that those ofordinary skill in the art may better understand the aspects of thepresent disclosure. Those of ordinary skill in the art should appreciatethat they may readily use the present disclosure as a basis fordesigning or modifying other processes and structures for carrying outthe same purposes and/or achieving the same advantages of theembodiments introduced herein. Those of ordinary skill in the art shouldalso realize that such equivalent constructions do not depart from thespirit and scope of the present disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the present disclosure.

What is claimed is:
 1. A lithography apparatus, comprising: a waferchuck configured to hold a wafer; a fluid source configured to contain afluid to be applied towards the wafer during a lithography process; adispensing nozzle positioned above the wafer chuck and in fluidcommunication with the fluid source, the dispensing nozzle having anadjustable cross-section; and a mechanical mechanism operable to apply aforce towards an outer surface of the dispensing nozzle to change theadjustable cross-section.
 2. The lithography apparatus of claim 1,wherein the mechanical mechanism includes elongated pins, and whereineach of the elongated pins is movable to be in physical contact with theouter surface of the dispensing nozzle.
 3. The lithography apparatus ofclaim 2, wherein each of the elongated pins is movable in a directionperpendicular to a lengthwise direction of the dispensing nozzle.
 4. Thelithography apparatus of claim 2, wherein the elongated pins are groupedin multiple layers stacked along a lengthwise direction of thedispensing nozzle.
 5. The lithography apparatus of claim 1, wherein themechanical mechanism is operable to change the adjustable cross-sectionon-the-fly during a dispensing operation of the lithography apparatus.6. The lithography apparatus of claim 1, wherein the fluid is aphotoresist or a photoresist developer.
 7. The lithography apparatus ofclaim 1, wherein a shape of the adjustable cross-section is selectedfrom a triangle, a rectangle, a square, a circle, an oval, or a polygon.8. The lithography apparatus of claim 1, further comprising: a gassprayer in a proximity region of an orifice of the dispensing nozzle,wherein the gas sprayer is operable to spray a gas to adjust an ambientpressure in the proximity region.
 9. The lithography apparatus of claim8, wherein the gas is an inert gas.
 10. The lithography apparatus ofclaim 1, further comprising: a movable arm attached to the dispensingnozzle, the movable arm being operable to move the dispensing nozzlehorizontally and vertically with respect to the wafer chuck.
 11. Anapparatus for dispensing a fluid during a lithography process,comprising: a wafer chuck; a nozzle positioned above the wafer chuck,the nozzle being operable to dispense the fluid towards the wafer chuck,the nozzle including an inner layer and an outer layer, the inner layerdefining a bore for the fluid to flow through the nozzle; movable pinsoperable to apply a force on the outer layer of the nozzle to change across-section of the bore, wherein the outer layer separates the movablepins from the inner layer; and a fluid source coupled to the nozzle, thefluid source containing the fluid.
 12. The apparatus of claim 11,wherein the movable pins are driven by applying a gaseous pressure. 13.The apparatus of claim 11, wherein the inner and outer layers of thenozzle include elastic films made of different material compositions.14. The apparatus of claim 13, wherein the elastic film of the innerlayer is more rigid than that of the outer layer.
 15. The apparatus ofclaim 11, wherein the fluid is a photoresist or a photoresist developer.16. A lithography apparatus for semiconductor manufacturing, comprising:a wafer chuck configured to support a wafer; a fluid source configuredto contain a fluid selected from a photoresist or a photoresistdeveloper; a delivery conduit in fluid communication with the fluidsource; and a dispensing outlet positioned above the wafer chuck, thedispensing outlet including at least two orifices, each orifice having adifferent cross-sectional shape, wherein the delivery conduit isoperable to be in fluid communication with one and only one of the atleast two orifices for the fluid to flow through.
 17. The lithographyapparatus of claim 16, wherein the dispensing outlet includes a maintube having one end coupled to a plurality of branch tubes, each of thebranch tubes is in fluid communication with a corresponding one of theat least two orifices, and the main tube has another end coupled to thedelivery conduit.
 18. The lithography apparatus of claim 17, wherein thedispensing outlet further includes a plurality of control valves, eachof the control valves is configured to control a fluid communicationpath of a corresponding one of the branch tubes.
 19. The lithographyapparatus of claim 16, wherein the dispensing outlet includes aplurality of branch tubes, each of the branch tubes has one end coupledto a corresponding one of the at least two orifices and another end thatcan be latched to the delivery conduit.
 20. The lithography apparatus ofclaim 16, wherein the dispensing outlet includes three orifices withdifferent cross-sectional shapes.